JPS62225905A - Method for measuring thickness - Google Patents

Abstract

PURPOSE:To measure a thickness without cutting a granular solid such as a concrete layer, by striking an article to be measured in the vicinity of the piezoelectric transducer with an electrode superposed onto said article and calculating the thickness of the article to be measured on the basis of first and second output signals obtained from the electrode. CONSTITUTION:A piezoelectric transducer A is constituted by applying polarization to a piezoelectric plate 1 comprising barium titanate and a piercing hole 3 is formed to the center thereof and ring-shaped electrodes 5, 7 are formed to both main surfaces thereof while a conductive reinforcing plate 11 is laminated to the electrode 7 in a contact state and lead wires 9, 13 are led out from the electrode 5 and the reinforcing plate 11. The piezoelectric transistor A is superposed to the surface of a concrete layer 15 being an article to be measured and the surfaces of the concrete layer 15 demarcated by a piercing part 14 are striken by a hammer to impart impact to said concrete layer 15. The time difference between a first signal (a) transmitted directly and a second signal (b) transmitted after reflection are detected by the lead wires 9, 13 to measure a thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thickness measuring method suitable for measuring the thickness of a solid layer made of hardened granular solids, such as a concrete layer.

[Conventional technology]

For example, if a road is paved with concrete.

After construction, it is necessary to confirm whether the concrete layer has been constructed to the specified thickness.

Conventionally, when measuring the thickness of such a concrete layer, the concrete layer was generally cut into a circular shape with a diameter of approximately 10 cm from the front surface to the back surface using a special cutter, and the depth of the cylindrical hole after cutting was measured. A commonly used method is to measure the length of a cylindrical part or to measure the length of a cylindrical part extracted from a cylindrical hole.

[Problem that the invention seeks to solve]

However, it takes a long time to cut the concrete layer with a cutter in this way, and the cylindrical hole after cutting needs to be filled again, making the process tedious and inefficient.
It is difficult to reduce the application cost by 1 or more.

The present invention has been made in order to solve these conventional drawbacks, and is designed to easily and inexpensively measure the thickness from the surface of a solid layer made of hardened granular solids such as a concrete layer without making holes. This is what I did.

[Means for solving problems]

In order to solve these problems, the thickness measuring method of the present invention uses a piezoelectric transducer A in which electrodes 5.7 are formed on a plate-shaped piezoelectric plate 1, as shown in FIGS. 1 to 5. After placing the piezoelectric transducer A on the surface of the object to be measured 15 such as a concrete layer, impact is applied to the object to be measured 15 by hitting the surface of the object to be measured 15 near the piezoelectric transducer A, and immediately after applying the impact, the above-mentioned The thickness of the object to be measured 15 is determined from the first output signal obtained from the electrode 5.7 and the second output signal obtained from the electrodes 5 and 7 due to impact vibration reflected from the back surface of the object to be measured 15. This is what we seek.

[For production]

According to such means, when an impact is applied to the object to be measured 15, vibrations corresponding to the impact are transmitted to the piezoelectric plate 1 of the piezoelectric transducer A, causing distortion, and an electrical signal is output to the electrodes.

Then, an electric signal is output from the electrode 5.7 due to the vibration immediately after the impact is applied or the delayed reflected vibration from the back surface of the object to be measured 15.

〔Example〕

The present invention will be explained in detail below.

1 to 4 are process diagrams showing an embodiment of the thickness measuring method of the present invention.

First, in the present invention, a disk-shaped piezoelectric transducer A as shown in FIGS. 1 and 2 is prepared. This piezoelectric transducer A is made of barium titanate (BaT).
A piezoelectric plate 1 made of iOs) is polarized, and a through hole 3 is formed in the center of the plate to pass through the opposing amphiboid surfaces.

This through hole 3 is formed when a piezoelectric transducer A is stacked on a concrete layer 15 as described later.

It has sufficient dimensions to allow the hammer 17 to hit the surface of the concrete 1-ii15 without contacting the piezoelectric plate 1. For example, a piezoelectric plate 1 with a diameter of about 5 to 10 cm has a thickness of 2 to 5 cm.
A through hole 3 of about 100 mL is formed.

Ring-shaped electrodes 5.7 are formed on both sides of the piezoelectric plate 1 so as to surround each through-hole 3, and a lead wire 9 is led out from one of the electrodes 5.7.

On the other electrode 7 side of the piezoelectric plate 1, a circular conductive reinforcing plate 11 with a larger diameter than the piezoelectric plate 1 is attached so as to be in contact with the electrode 7, and a lead wire is connected from the edge of the reinforcing plate 11. ■3 has been derived.

Note that an M through hole 1o having the same diameter or a slightly larger diameter than the through hole 3 of the piezoelectric plate 1 is formed in the reinforcing plate 11, and the reinforcing plate 11 is attached so as to be aligned with the through hole 3 of the piezoelectric plate 1. , a through hole 14 is formed in each through hole 3.10.

Next, as shown in FIG.
are stacked on the surface of the concrete layer 15 so that the reinforcing plate is in contact with the surface of the concrete layer 15. Note that the piezoelectric transducer A in the drawings below is shown schematically, and the electrodes 5.7 are omitted.

Thereafter, in this state, as shown in FIG. 4, the surface of the concrete N15 divided by one penetration 5 and one part 14 is struck with a hammer 17 to apply an impact.

Then, in the piezoelectric transducer A, the impact vibration is transmitted to the piezoelectric plate 1 through the concrete 1ii15, the piezoelectric plate 1 is distorted, and an electric signal is obtained from the electrode 5.7.

This electrical signal is 1, for example as shown in FIG.

Immediately after hitting with the hammer 17, the first electric signal (a) due to the impact vibration is transmitted to the piezoelectric plate 1 over the shortest distance, and the first electric signal (a) is transmitted through this concrete layer 15, reflected on the back surface, propagated to the surface again, and is transmitted to the piezoelectric plate 1. There is a second electrical signal (b) generated by distorting the first electrical signal, and a third electrical signal (c) resulting from a reflected wave that has been reflected multiple times.

Then, such first and second electrical signals (a),
(b) The thickness of the concrete layer 15 is measured by determining the time difference.

Note that the thickness measuring method of the present invention can also be carried out by using a piezoelectric transducer that does not have the through portion 14 and striking the vicinity of the piezoelectric transducer. but,
A piezoelectric transducer A having a first through-hole 14
When using the concrete layer 15, when it is overlapped with the concrete layer 15, the surface of the concrete layer 15 is partially partitioned by the penetration part 14, so the tapping position can also be determined, improving workability and measurement accuracy.

Furthermore, the piezoelectric plate 1 of the piezoelectric transducer A used in the thickness measuring method of the present invention is not limited to barium titanate, and can be formed of a wide variety of general piezoelectric materials.

Its shape is not limited to a circle, but any arbitrary shape, such as a square, can be selected. The electrodes 5.7 also do not need to be formed on the opposing main surfaces of the piezoelectric plate 1, and can be formed only on one side of the piezoelectric plate 1.

Furthermore, the reinforcing plate 11 of the piezoelectric transducer A is not essential. However, since the concrete layer 15 is tapped when measuring the thickness, if the reinforcing plate 11 is attached to the piezoelectric plate 1, the piezoelectric plate 1
strength is significantly improved.

When the electrodes 5.7 are formed on the opposing main surface of the piezoelectric plate 1, the lead wire 13 can be led out from the edge of the reinforcing plate 11, so that the thickness measurement transducer A can be firmly attached to the surface of the concrete N15. This allows for accurate measurements.

Next, an example of the thickness measuring device used in the thickness measuring method of the present invention will be shown and the procedure for carrying out the above-mentioned thickness measuring method will be explained.

FIG. 6 is a block diagram showing a thickness measuring device B using the piezoelectric transducer A of the present invention.

The shaping circuit 19 connected to the piezoelectric transducer A is
Waveform shaping the electrical signal from piezoelectric transducer A,
This is a circuit that outputs a pulse signal when a signal of a predetermined level or higher is input, and is connected to the counter circuit 21. For example, 1. Second electrical signal (a)
, (b) according to the first. A second pulse signal is output to the counter circuit 21.

The counter circuit 21 has a function of starting counting in response to the first pulse signal from the shaping circuit 19, measuring the time until the second pulse signal, and outputting the time signal to the comparison circuit 23.

The comparator circuit 23 includes a memory circuit 2 in addition to the counter circuit 21.
5 is connected. The memory circuit 25 is.

As shown in FIG. 7, each thickness dimension of the concrete layer 15 and the first thickness actually measured by adding the surgical area to the concrete layer 15.
This circuit stores time difference data between second pulse signals in advance.

The comparison circuit 23 is connected to the CP of the microcomputer.
The signal from the counter circuit 21 is compared with the data from the memory circuit 25, and proportional calculation is performed based on the thickness data of the memory circuit 25 closest to the value from the counter circuit 21 or the signal from the memory circuit 25. It has a function of outputting the displayed value to the display circuit 27.

Note that the second display circuit 27 includes a display such as a liquid crystal or an LED, and is a circuit that displays the actual thickness in numbers or the like based on the thickness signal from the comparison circuit 23.

Next, the measurement operation in such thickness measuring device B will be explained.

First, as shown in FIG. 4, when the surface of the concrete layer 15 divided by the penetration part 14 of the piezoelectric transducer A is struck with the hammer 17, a first electrical signal is output from the piezoelectric transducer A. A first pulse signal is applied from the shaping circuit 19 to the counter circuit 21 to start counting nine hours.

Thereafter, the impact vibration propagated through the concrete layer 15 is reflected on the back surface and transmitted to the piezoelectric plate 1, generating a second electrical signal in the piezoelectric transducer A, and a second pulse signal is output from the shaping circuit 19 to the counter circuit 21. be done. Then, a signal corresponding to the time difference between the first and second pulse signals is outputted from the counter circuit 21 to the comparison circuit 23.

The comparison circuit 23 displays the thickness data of the memory circuit 25 closest to the signal from the counter circuit 21 based on the time data from the memory circuit 25, or a value calculated proportionally based on the signal from the memory circuit 25. Output to circuit 27. The display circuit 27 displays the thickness numerically based on the signal.

Note that if the concrete layer 15 has multiple layers, it is possible to measure the thickness of each layer by counting the time of impact vibration reflected after a slight delay, and the thickness of each layer can be measured by counting the time of the impact vibration reflected after a slight delay. The thickness of concrete N15 can be measured not only from the time difference between electrical signals, but also from the difference in level or waveform between the first electrical signal and the second electrical signal. Just change it.

FIG. 8 shows an application example of the present invention, in which a plurality of piezoelectric transducers A1 to A4 are used to measure a plurality of items in the concrete layer 15.

That is, a piezoelectric transducer A as shown in FIG.
Let be the first piezoelectric transducer A.

Another second to fourth piezoelectric transducer A2 having no penetration part at an angle of 120° around this as a center.
A4 is placed on the surface of the concrete layer 15, and the surface of the concrete layer 15 divided by the penetration part 14 of the first piezoelectric transducer A1 is struck, and the thickness of the concrete layer 15 is measured by the electrical signal from the first piezoelectric transducer A1. While measuring, the first piezoelectric transducer A
1 and second to fourth piezoelectric transducers A2 to A4
This also makes it possible to measure the propagation constant of the concrete layer 15 using electrical signals from the concrete layer 15.

Note that the reference numeral 29 in FIG. 8 indicates each piezoelectric transducer A1.
~This is an instruction member that supports A4 and also serves as a lead part.

In such a configuration, it is possible to measure the thickness of the concrete 7515 as described above, and the first piezoelectric transducer A can be used immediately after applying an impact.

The time difference between the signal obtained from the second to fourth piezoelectric transducers A2 to A4 is measured, and the propagation constant of the concrete 1-itf15 can be measured based on this time difference. For example, the measurement may be performed by comparing a time difference that has been quickly set in advance in concrete layers 15 having different propagation constants. Based on this propagation constant, the mixing ratio of gravel and sand in the concrete layer 15 can be estimated.

By the way, conventionally, ultrasonic waves are emitted to an object to be measured.

The depth is determined by measuring the time it takes for the ultrasound to return.

Although length, thickness, etc. are measured.

The method using ultrasonic waves is suitable for liquids, etc., but in the case of a solid layer such as the concrete layer 15 made of hardened granular solids, the ultrasonic waves are likely to be diffusely reflected by the granular solids, making measurement impossible.

Point 1: If the object to be measured is struck and the impact vibration is measured as in the present invention, the measurement can be performed easily and reliably, and therefore it is suitable for measuring the thickness of a solid layer made of hardened granular solids such as the concrete layer 15.

〔Effect of the invention〕

As explained above, the thickness measuring method of the present invention is as follows.

It is possible to measure the thickness of an object by simply placing a piezoelectric transducer using a piezoelectric plate on top of the object and tapping the surface of the object. This eliminates the need to cut the concrete layer to form holes, making it quick and easy. Thickness can be easily measured, its efficiency is high, and construction costs can be reduced.

[Brief explanation of drawings]

1 to 4 are process diagrams showing an embodiment of the thickness measuring method of the present invention, and in particular, FIGS. 1 and 2 show an embodiment of a piezoelectric transducer used in the thickness measuring method of the present invention. A perspective view and a longitudinal cross-sectional view. FIG. 5 is a diagram showing an example of an electric signal obtained from the piezoelectric transducer of FIG. 1, FIG. 6 is a block diagram showing an example of a thickness measuring device used in the thickness measuring method of the present invention, and FIG. FIG. 8 is a diagram showing the storage state of data stored in the storage circuit of FIG. 8, and FIG. 8 is a diagram showing another embodiment of the thickness measuring transducer of the present invention. 1...Piezoelectric plate 3.10.14.Penetration part (tributary hole) 5.7..Electrode 11..Reinforcement plate 15..Object to be measured (concrete layer) 17.Life--
Hammer 19... Shaping circuit 21... Counter circuit 23... Comparison circuit 25... Memory circuit 27... Display circuit A... Thickness measurement transducer B... Thickness Measuring Device Patent Applicant Chuo Denshi Kogyo Co., Ltd. Representative Patent Attorney Miharu Saito Figure 5 Figure 6 Figure 7 Figure 8

Claims (2)

[Claims] (1) A first step in which a piezoelectric transducer, which is formed by forming electrodes on a plate-shaped piezoelectric plate, is placed on the surface of the object to be measured; a second step of applying an impact; a first output signal obtained from the electrode immediately after applying the impact in this second step; and a first output signal obtained from the electrode by impact vibration reflected by the object to be measured. a third step of determining the thickness of the object to be measured from the output signal of step 2; (2) The thickness measuring method according to claim 1, using a piezoelectric transducer having a penetration part and hitting the surface of the object to be measured defined by the penetration part.